A liquid crystal display in general comprises a polarizing plate and a liquid crystal cell. In a TN mode TFT liquid crystal display which is the mainstream now, a liquid crystal display of high grade display has been realized by the technique of inserting an optical compensating film between a polarizing plate and a liquid crystal cell as disclosed in JP-A-8-50206 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). However, there is a drawback in this technique that the thickness of a liquid crystal display itself becomes thick.
There is disclosed in JP-A-1-68940 that it is possible to make front contrast high without thickening liquid crystal display by using an oval polarizing plate comprising a polarizing film having a phase contrast plate on one surface and a protective film on the other surface. However, it has been found that the phase contrast film disclosed in this patent is liable to cause phase difference due to distortion by heat, and so there is a problem in durability.
The problem of generation of phase difference due to distortion has been solved by the technique of directly using an optical compensating film comprising a transparent support having coated thereon an optical anisotropic layer comprising a discotic compound as the protective film of a polarizing plate as disclosed in JP-A-7-191217 and EP-A-0911656.
However, a problem that the downward gradation reverse of a panel occurs in the liquid crystal display still remains.
With respect to this problem, the grade of display has been greatly improved by providing a light-diffusing means on the surface of viewer's side as disclosed in Japanese Patent 2822983, JP-A-2001-33783 and JP-A-2001-56461. However, as the specific light-diffusing means according to these patents, highly controlled lens structure or a light-diffusing means having diffraction structure are necessary, which means are very expensive and mass production is extremely difficult.